Electrical connector



July 29, 1969 J. F. VQLKER 3,458,648-

.ELECTRICAL CONNECTOR Filed Oct. ll, 1967 f f5 y Ele-2. l Z7 K6 Z7 KZ y15 9 j? f f f f 75 W ffl' INVENTOR. JOHN VQLKER United States Patent OU.S. Cl. 174-88 9 Claims ABSTRACT F THE DISCLOSURE A connector assemblyfor joining a pair of metallic sheathed electrical conductors inend-to-end relation with the sheaths spaced axially apart and includinga metallic sleeve extending between and connecting respective adjoiningsheath ends. The sleeve provides a pair of transverse apertures incommunication with the space between the conductor sheaths and theapertures are spaced axially along the sleeve. The interior of thesleeve is completely iilled with a fluid dielectric, spherical plugs areforce-fitted into respective apertures to close the same, and a clampencircles the sleeve for retaining the plugs in respective apertures.Disposed within the sleeve, in an annular space between the latter andrespective conductors, is a dielectric sleeve member which, incombination with the fluid dielectric, reduces the possibility thatelectrical energy will jump the gap between the electrical conductorsand the metallic sleeve.

Preamble The use of mineral insulated cables, both heating cables andpower transmission cables, has rapidly increased in recent years givingrise to the necessity of development of a satisfactory structure forjoining such cables together in the ield. Since mineral insulated cablesare designed for use under severe conditions, any connection joiningsuch cables must also be capable of functioning under such conditions.Heretofore, field-made connections between mineral insulated cables havebeen diflicult and time-consuming to make and have frequently not metthe required high quality standards. In the past, it has all toofrequently been necessary to dismantle a completed con nection and startover again.

The present invention simplifies making connections between mineralinsulated cables under field conditions and is adequate for factoryinstallation as well. The advantages of the present invention willreadily become apparent from a study of the following description andfrom the appended drawings.

Description of the drawings In the drawings accompanying thisspecification and forming a part of this application there is shown, forpurpose of illustration, embodiments which the invention may assume, andin these drawings:

FIGURE l is a side elevational view of a connection 0f the presentinvention between a pair of mineral insulated cables,

FIGURE 2 is a longitudinal sectional view through the structure seen inFIGURE 1,

FIGURES 3 and 4 are sectional views similar to FIG- URE 2 but atpreliminary assembly stages, and

FIGURE 5 is a view similar to FIGURE 2 but of another embodiment of theinvention.

Detailed description With reference to FIGURES 1 and 2, a pair ofmineral insulated, metallic sheathed cables 10` and 10.1 are shownjoined together in end-toend relation by a connector assembly 11. Asillustrated in FIGURE 2, each cable may be of the well-known type havingrespective tubular metallic sheaths 12 filled with highly compactedelectric-insulating refractory material 13 such as powdered magnesiumoxide. Centrally disposed within each tubular sheath 12 and embedded inthe material 13 are respective electrical conductors 14 which projectaxially beyond respective sheath ends. The free ends of conductors 14are disposed in abutting relation and are connected together, as bybrazing at 15, to provide a strong joint of minimum electricalresistance.

Extending between and hermetically joined to respective cable sheaths isa metallic sleeve 16, having a first portion 17 of an internal size toclosely but slidably t over the sheath of cable 10', and a secondportion 18 having a bore 19 of a size materially larger than that of thecable sheaths. Closely encircling a portion of the sheath of cable 10.1adjacent its end is a tubular metallic spacer 20 whose exterior isdimensioned to closely tit within the sleeve bore 19. The arrangement issuch that a chamber 21 is provided within the sleeve 16 in which aredisposed the abutting ends of conductors 14 and the adjoining ends ofthe cable sheaths 12.

As previously mentioned, the sleeve 16 is hermetically joined torespective cable sheaths and as herein disclosed, sleeve portion 17 iswelded at 22 to the sheath of cable 10 while the sleeve portion 18 isWelded at 23 to the tubular spacer 20 which is in turn welded to thesheath of cable 10.1 at 24. To insure complete sealing, the Welds 22, 23and 24 are, of course, annular.

In order to reduce the possibility of arcing between the conductors 14and the sleeve 16, a dielectric sleeve 25 is preferably disposed aboutthe exposed conductors and within the chamber 21. For a purpose toappear, the ends of the dielectric sleeve are cut at an angle of lessthan degrees with its axis.

To further reduce the possibility of arcing between the conductors 14and the sheath ends or between such conductors and the sleeve 16, thepreviously mentioned sleeve chamber 21 is completely filled with adielectric iiuid such as heavy oil or grease. At the present time it ispreferable to lill the chamber with a silicon grease which has thenecessary dielectric qualities along with the requisite temperatureresistance. T o provide for introduction of the dielectric iiuid intothe chamber 21, sleeve 16 is, at best seen in FIGURE 3, provided withaxially spaced, transversely extending apertures 26 in communicationwith chamber 21. In FIGURE 2, apertures 26 are shown plugged byrespective balls 27.

For retaining balls 27 in respective apertures and for another purposeto later appear, a conventional clamp 28 encircles the sleeve 16 and istightly drawn thereabout. Since the clamp presently used is not wideenough to span the apertures 26, a metal strip 29 which is arcuate incrosssection overlies the apertures and underlies the clamp. Obviously,strip 29 could be omitted by using two clamps or by using a single clampwide enough to span the apertures 26.

To form the assembly seen in FIGURES 1 and 2, the

cables 10, 10.1 will be disposed in end-to-end relation with respectiveconductors 14 abutting each other and with the metallic sleeve 16, thedielectric sleeve 25 and the spacer 20 assembled on the abutted cablesas illustrated in FIG- URE 3. The conductors 14 will then be brazedtogether at 15 and the spacer 20 will be welded at 24 to the sheath ofcable 10.1 by the annular weld 24 as shown. If more convenient, spacer29 may be welded to cable 10.1 prior to disposition of the cables inend-to-end relation and prior to welding of the conductors 14.

With the conductors welded together, dielectric sleeve 25 will be slidto the right from the position of parts seen in FIGURE 3 along theconductors to span the gap between respective cable sheaths. The sleeve16 will then similarly be slid to the right until the bottom of its bore19 abuts the dielectric sleeve 25 and the latter abuts the adjoining endof spacer 20. Annular welds 22, 23 will next be made to hermeticallysecure the sleeve 16 to the sheath of cable 10 and the spacer 20respectively.

With the parts thus assembled and with reference to FIGURE 4, thedielectric fluid may be introduced into the chamber 21 through one ofthe apertures 26fwhile air is displaced from the chamber through theother aperture 26. It will be understood that with the dielectric sleeveends cut at an angle, both ends of the sleeve will be open despite theirabutment with the bottom of sleeve bore 19 and the end of spacer 20 sothat the dielectric fluid will freely enter the sleeve and the containedair will freely escape therefrom.

Before disclosing the final assembly operation, it is pointed out thatthe sleeve apertures 26 are preferably cylindrical, as by being formedin a drilling operation. The apertures 26 and balls 27 are soproportioned that the latter have an interference fit with the former,that is, the balls are of a slightly larger diameter than the diameterof the apertures.

Assuming that the sleeve chamber is filled with the dielectric fluid ashereinabove described, the balls 27 are ready to be forced intorespective apertures 26 for sealing purposes. An ordinary pair of pliersmay be used to force the balls in place, one jaw J1 of the pliersengaging a ball 27 as seen in FIGURE 4, and the opposite jaw I2 bearingagainst the diametrically opposite outer surface of the portion 18 ofsleeve 16. When pressure is applied by the jaws Il-JZ the ball 27 isforced into the aperture and since the wall thickness of the sleeve isgreater than onehalf the diameter of the ball, the latter cannot beforced through the aperture by the pliers.

The sleeve 16 is usually formed of a relatively soft metal and the ballsare usually of hardened steel so that when a ball is formed into aninterference fit aperture, zero clearance results therebetween and agood seal is made. When the joint is subjected to heat, the siliconegrease may expand enough to create an internal pressure which would tendto pop the balls out of their seats. 'Ihe addition of the strip 29 andthe clamp 28 will prevent any such popping action. Also, when the jointis subjected to heat, the clamp 28 may expand and thus allow the balls27 to slightly back out of their fully seated position in the apertures26. However, since the balls were pressed to zero clearance fit in theapertures, they may move a slight amount backward without disturbing theseal.

'Ihe embodiment of FIGURE 5 is similar to that heretofore disclosed andtherefore corresponding parts are identified by the same referencecharacters but with the suffix a added. In this embodimeneach cable 10a,10.1a is provided with two conductors 14a in sidebyside relation insteadof the single conductor heretofore disclosed. Furthermore, to reduce thepossibility of electrical breakdown between the side-by-side conductors,a strip of dielectric material 30 is disposed between such conductors.Strip 30, of course, will be dimensioned to fit between the adjoiningends of respective cable sheaths and will further be dimensioned toclosely fit within the dielectric sleeve 23g. Such strip 30 will thus beconfined against displacement from the position shown.

While the embodiments hereinabove disclosed show the connection ofcables which are the same size, it will readily be apparent that cablesdiffering in size from each other may readily be connected. For example,if a smaller cable 10.1 is to be joined to the cable 10, a spacer 20having an appropriately smaller inside diameter may be employed.Similarly, if cable 10.1 should be larger, the spacer 20 may be providedwith an appropriately larger inside diameter.

I claim: 1. A connector assembly for a pair of metallic sheathedelectrical conductors disposed in end-to-end relation wherein theconductors extend axially beyond the ends of respective sheaths and aresecured together in electrical continuity, wherein respective sheathends are disposed in axially spaced relation, and wherein a transverselyapertured metallic sleeve extends between adjoining sheath ends and issecured thereto in fluid-tight relation,

the improvement wherein the transverse aperture in said sleevecommunicates with the space between respective sheath ends, j

wherein the interior of said sleeve and the space between said sheathends is filled with a liuid dielectric, wherein said sleeve transverseaperture is closed by a plug,

and wherein retaining means maintains said plug in said sleeve apertureand prevents escape of said dielectric Huid.

2. The construction of claim 1 wherein said plug and the defining wallsof said sleeve transverse aperture have press fit engagement,

and wherein said retaining means comprises a clamp for holding said plugin engagement with the defining walls of said sleeve aperture.

3. The construction of claim 1 wherein said sleeve is formed of arelatively soft metal and said sleeve aperture is cylindrical,

wherein said plug comprises a ball of a relatively hard metal and of adiameter slightly larger than the diameter of said aperture and ispressed into the latter and has zero clearance therewith to form a seal,

.and wherein said retaining means comprises a clamp holding said ballwithin said sleeve aperture.

4. The construction of claim 3 wherein said clamp comprises a bandencircling said sleeve.

5. The construction of claim 1 wherein said sleeve has a pair oftransverse apertures spaced from each other longitudinally of saidsleeve, one of said apertures providing for injection of said dielectricfluid into said sleeve interior and said other aperture providing fordisplacement of air from said sleeve interior.

6. The construction of claim 5 wherein each sleeve aperture is closed byrespective plugs having wedged interengagement therein,

wherein said retaining means comprises a band encircling said sleeve,

and wherein a rigid member extends between and overlies said sleeveapertures, said member underlying said band and being drawn therebyagainst said sleeve to hold said plugs within respective apertures.

7. The construction of claim 6 wherein the connections between saidmetallic sleeve and respective sheaths are of the metallic fused type.

8. A connector assembly for a pair of metallic sheathed electricalconductors disposed in end-to-end relation wherein the conductors extendaxially beyond the ends of respectivesheaths and are secured together inelectrical continuity, wherein respective sheath ends are disposed inaxially spaced relation, and wherein a transversely apertured metallicsleeve extends between adjoining sheath ends and is secured thereto influid-tightrelation,

the improvement wherein the transverse aperture in 5 6 said sleevecommunicates with the space between reand wherein said dielectric sleeveis completely filled spective sheath ends, with said dielectric uid andis completely surrounded wherein the interior of said sleeve and thespace bethereby.

tween said sheath ends is lled with a fluid dielectric, References Citedwlellllegn said sleeve transverse aperture is closed by a 5 UNITEDSTATES PATENTS and wherein a dielectric sleeve is disposed within said212471671 7/1941 TePl --7 17476 XR metallic sleeve in encirclingrelation with said elec- 312431500 3/1966 Rabmowltz 174-88 XR tricalconductors. 9. The construction of claim 8 wherein said dielectric 10DARRELL L' CLAY Primary Examiner sleeve is larger in diameter than saidsheath ends and ex- U s C1 X R tends therebetween,

wherein said dielectric sleeve is smaller in diameter than 174--21, 76,91

said metallic sleeve,

